Role of Epithelial Cells in Initiation and Propagation of Intestinal Inflammation. Eliminating the static: tight junction dynamics exposed

2006 ◽  
Vol 290 (4) ◽  
pp. G577-G582 ◽  
Author(s):  
Le Shen ◽  
Jerrold R. Turner
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Tight Junctions ◽  
Plasma Membranes ◽  
Intestinal Inflammation ◽  
Intestinal Barrier ◽  
Barrier Properties ◽  
Structural Modifications ◽  
Mucosal Surfaces

Like all mucosal surfaces, the intestine forms a barrier that separates the external environment, i.e., the gut lumen, from the protected internal milieu. The intestinal barrier is formed by the epithelial cells that line the luminal surface. Plasma membranes of these cells prevent free passage of hydrophilic molecules across this barrier but do not seal the space between cells. This function is provided by the tight junction. Each cell is encircled at the apicolateral boundary by the tight junction, which seals the paracellular space. The tight junction does not form a completely impermeant seal, however, because that would prevent paracellular absorption of essential nutrients and ions; intestinal tight junctions are “leaky” and allow solutes to be transported paracellularly according to size and charge. Abundant data are available to demonstrate that barrier properties of tight junctions can be modulated in response to physiological, pharmacological, and pathophysiological stimuli, but the structural modifications responsible for these responses are poorly defined. Recent advances in understanding the role of tight junction dynamics in response to such stimuli are the focus of this review.

Role of Na-K-ATPase in the assembly of tight junctions

2003 ◽  
Vol 285 (3) ◽  
pp. F388-F396 ◽  
Author(s):  
Ayyappan K. Rajasekaran ◽  
Sigrid A. Rajasekaran
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Tight Junctions ◽  
Mammalian Cells ◽  
Actin Polymerization ◽  
Normal Function ◽  
Stress Fibers ◽  
Rhoa Gtpase ◽  
Step Model

Na-K-ATPase, also known as the sodium pump, is a crucial enzyme that regulates intracellular sodium homeostasis in mammalian cells. In epithelial cells Na-K-ATPase function is also involved in the formation of tight junctions through RhoA GTPase and stress fibers. In this review, a new two-step model for the assembly of tight junctions is proposed: step 1, an E-cadherin-dependent formation of partial tight junction strands and of the circumferential actin ring; and step 2, active actin polymerization-dependent tethering of tight junction strands to form functional tight junctions, an event requiring normal function of Na-K-ATPase in epithelial cells. A new role for stress fibers in the assembly of tight junctions is proposed. Also, implications of Na-K-ATPase function on tight junction assembly in diseases such as cancer, ischemia, hypomagnesemia, and polycystic kidney disease are discussed.

GENETIC SUSCEPTIBILITY TO IBD OPERATES VIA CONTROL OF APICAL JUNCTIONAL COMPLEXES

2021 ◽  
Vol 27 (Supplement_1) ◽  
pp. S30-S30
Author(s):  
Isabelle Hébert-Milette ◽  
Chloé Lévesque ◽  
Guy Charron ◽  
John Rioux
Keyword(s):  
Tight Junction ◽  
Tight Junctions ◽  
Intestinal Inflammation ◽  
Protein Localization ◽  
Junctional Complex ◽  
Epithelial Permeability ◽  
3D Cultures ◽  
Apical Junctional Complex ◽  
Junction Protein ◽  
The Impact

Abstract Introduction Intestinal permeability is increased in unaffected 1st degree relatives of patients with inflammatory bowel disease (IBD), and is considered a risk factor for the development of IBD, likely increasing the interactions between intestinal microorganisms and the immune system. We recently reported that C1orf106, a gene located within a genomic region associated with IBD, regulates epithelial permeability. We further demonstrated that a rare coding variant within C1orf106 (p.Y333F) decreases protein stability and that lower levels of C1orf106 protein leads altered stability of adherens junctions (AJ) and to an increase in epithelial permeability. Hypothesis In addition to altering AJ, we believe that C1orf106 is also involved in the regulation of tight junction (TJ) formation, which also impacts epithelial permeability. Objectives The objectives of the project are to (a) validate the impact of C1orf106 on tight junctions and (b) verify the impact of C1orf106 IBD-associated variants on intestinal barrier integrity. Results We observed that knocking down the expression of C1orf106 in Caco-2 cells leads to a number of phenotypes in human epithelial monolayer (2D) and spheroid (3D) cultures that are associated with alterations in TJs. Specifically, when studying the dynamic reformation of TJ in 2D cultures after transient withdrawal of calcium, which is required for TJ stability, we observed that lower levels of C1orf106 resulted in (1) decreased recovery of barrier function as measured by transepithelial electrical resistance (TEER); (2) an alteration of tight junction protein localization; and (3) thickening of the circumferential actin belt. Moreover, in 3D cultures, we observed an altered spheroid formation associated with impaired epithelial polarization. In addition, our preliminary studies of human induced pluripotent stem cell (hiPSC)-derived epithelial cultures support that Y333F heterozygotes also have altered structure and function of their tight junctions. Conclusion Our observations indicate an important role of C1orf106 in apical junctional complex (AJC) formation likely mediated by a regulation of the circumferential actin belt. This can affect other functions of AJC, like the establishment of cell polarity. AJC formation is important for epithelial repair after an injury and its dysregulation impairs the formation of an impermeable epithelial barrier, which likely facilitates the passage of microorganisms and the induction and maintenance of intestinal inflammation.

scholarly journals Role of nectin in organization of tight junctions in epithelial cells

2002 ◽  
Vol 7 (10) ◽  
pp. 1059-1072 ◽  
Author(s):  
Atsunori Fukuhara ◽  
Kenji Irie ◽  
Akio Yamada ◽  
Tatsuo Katata ◽  
Tomoyuki Honda ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junctions

Localization of a novel 210 kDa protein in Xenopus tight junctions

1997 ◽  
Vol 110 (8) ◽  
pp. 1005-1012 ◽  
Author(s):  
C.S. Merzdorf ◽  
D.A. Goodenough
Keyword(s):  
Monoclonal Antibody ◽  
Epithelial Cells ◽  
Tight Junction ◽  
Tight Junctions ◽  
Basolateral Membrane ◽  
Immunofluorescent Staining ◽  
Junctional Complex ◽  
Permeability Barrier ◽  
Membrane Domains ◽  
Kidney Liver

The tight junction is the most apical member of the intercellular junctional complex. It functions as a permeability barrier between epithelial cells and maintains the integrity of the apical and basolateral membrane domains. In order to study tight junctions in Xenopus laevis, a polyclonal antibody was raised which recognized Xenopus ZO-1. Monoclonal antibody 19B1 (mAb 19B1) was generated in rats using a crude membrane preparation from Xenopus lung as antigen. mAb 19B1 gave immunofluorescent staining patterns identical to those seen with anti-ZO-1 on monolayers of Xenopus A6 kidney epithelial cells and on frozen sections of Xenopus kidney, liver, and embryos. Electron microscopy showed that the 19B1 antigen colocalized with ZO-1 at the tight junction. Western blotting and immunoprecipitation demonstrated that ZO-1 is an approximately 220 kDa protein in Xenopus, while mAb 19B1 identified an approximately 210 kDa antigen on immunoblots. Immunoprecipitates of ZO-1 were not recognized by mAb 19B1 by western analysis. The solubility properties of the 19B1 antigen suggested that it is a peripheral membrane protein. Thus, the antigen recognized by the new monoclonal antibody 19B1 is not ZO-1 and represents a different Xenopus tight junction associated protein.

scholarly journals Tight Junction in the Intestinal Epithelium: Its Association with Diseases and Regulation by Phytochemicals

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Bonggi Lee ◽  
Kyoung Mi Moon ◽  
Choon Young Kim
Keyword(s):  
Tight Junction ◽  
Tight Junctions ◽  
Intestinal Epithelium ◽  
Essential Role ◽  
Inflammatory Diseases ◽  
Intestinal Barrier ◽  
Nutritional Factors ◽  
Nutritional Interventions ◽  
Intestinal Epithelia ◽  
Pathological Conditions

The intestine plays an essential role in integrating immunity and nutrient digestion and absorption. Adjacent intestinal epithelia form tight junctions (TJs) that are essential to the function of the physical intestinal barrier, regulating the paracellular movement of various substances including ions, solutes, and water across the intestinal epithelium. Studies have shown that TJ dysfunction is highly associated with metabolic and inflammatory diseases. Thus, molecular and nutritional factors that improve TJ activity have gained attention in the pharmaceutical and medicinal fields. This review focuses on the association between TJ and diverse pathological conditions, as well as various molecular and nutritional interventions designed to boost TJ integrity.

Physiological regulation of epithelial tight junctions is associated with myosin light-chain phosphorylation

1997 ◽  
Vol 273 (4) ◽  
pp. C1378-C1385 ◽  
Author(s):  
Jerrold R. Turner ◽  
Brian K. Rill ◽  
Susan L. Carlson ◽  
Denise Carnes ◽  
Rachel Kerner ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Tight Junctions ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Kinase Inhibitors ◽  
Tight Junction Regulation ◽  
Tight Junction Permeability ◽  
Mlc Phosphorylation

Tight junctions serve as the rate-limiting barrier to passive movement of hydrophilic solutes across intestinal epithelia. After activation of Na+-glucose cotransport, the permeability of intestinal tight junctions is increased. Because previous analyses of this physiological tight junction regulation have been restricted to intact mucosae, dissection of the mechanisms underlying this process has been limited. To characterize this process, we have developed a reductionist model consisting of Caco-2 intestinal epithelial cells transfected with the intestinal Na+-glucose cotransporter, SGLT1. Monolayers of SGLT1 transfectants demonstrate physiological Na+-glucose cotransport. Activation of SGLT1 results in a 22 ± 5% fall in transepithelial resistance (TER) ( P< 0.001). Similarly, inactivation of SGLT1 by addition of phloridzin increases TER by 24 ± 2% ( P < 0.001). The increased tight junction permeability is size selective, with increased flux of small nutrient-sized molecules, e.g., mannitol, but not of larger molecules, e.g., inulin. SGLT1-dependent increases in tight junction permeability are inhibited by myosin light-chain kinase inhibitors (20 μM ML-7 or 40 μM ML-9), suggesting that myosin regulatory light-chain (MLC) phosphorylation is involved in tight junction regulation. Analysis of MLC phosphorylation showed a 2.08-fold increase after activation of SGLT1 ( P< 0.01), which was inhibited by ML-9 ( P < 0.01). Thus monolayers incubated with glucose and myosin light-chain kinase inhibitors are comparable to monolayers incubated with phloridzin. ML-9 also inhibits SGLT1-mediated tight junction regulation in small intestinal mucosa ( P < 0.01). These data demonstrate that epithelial cells are the mediators of physiological tight junction regulation subsequent to SGLT1 activation. The intimate relationship between tight junction regulation and MLC phosphorylation suggests that a critical step in regulation of epithelial tight junction permeability may be myosin ATPase-mediated contraction of the perijunctional actomyosin ring and subsequent physical tension on the tight junction.

scholarly journals Apically Exposed, Tight Junction-Associated β1-Integrins Allow Binding and YopE-Mediated Perturbation of Epithelial Barriers by Wild-Type Yersinia Bacteria

2000 ◽  
Vol 68 (9) ◽  
pp. 5335-5343 ◽  
Author(s):  
Farideh Tafazoli ◽  
Anna Holmström ◽  
Åke Forsberg ◽  
Karl-Eric Magnusson
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Tight Junctions ◽  
Yersinia Pseudotuberculosis ◽  
Cell Structure ◽  
Wild Type ◽  
Filamentous Actin ◽  
Basolateral Membranes ◽  
Contact Points ◽  
Β1 Integrins

ABSTRACT Using polarized epithelial cells, primarily MDCK-1, we assessed the mode of binding and effects on epithelial cell structure and permeability of Yersinia pseudotuberculosis yadA-deficient mutants. Initially, all bacteria except the invasin-deficient (inv) mutant adhered apically to the tight junction areas. These contact points of adjacent cells displayed β1-integrins together with tight junction-associated ZO-1 and occludin proteins. Indeed, β1-integrin expression was maximal in the tight junction area and then gradually decreased along the basolateral membranes. Wild-type bacteria also opened gradually the tight junction to paracellular permeation of different-sized markers, viz., 20-, 40-, and 70-kDa dextrans and 45-kDa ovalbumin, as well as to their own translocation between adjacent cells in intimate contact with β1-integrins. The effects on the epithelial cells and their barrier properties could primarily be attributed to expression of the Yersinia outer membrane protein YopE, as the yopE mutant bound but caused no cytotoxicity. Moreover, the apical structure of filamentous actin (F-actin) was disturbed and tight junction-associated proteins (ZO-1 and occludin) were dispersed along the basolateral membranes. It is concluded that the Yersinia bacteria attach to β1-integrins at tight junctions. Via this localized injection of YopE, they perturb the F-actin structure and distribution of proteins forming and regulating tight junctions. Thereby they promote paracellular translocation of bacteria and soluble compounds.

Airway epithelial tight junctions and binding and cytotoxicity ofPseudomonas aeruginosa

1999 ◽  
Vol 277 (1) ◽  
pp. L204-L217 ◽  
Author(s):  
Alfred Lee ◽  
Dar Chow ◽  
Brian Haus ◽  
Wanru Tseng ◽  
David Evans ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junctions ◽  
Propidium Iodide ◽  
Time Course ◽  
Living Cells ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Basolateral Membranes ◽  
Free Edges

The role of tight junctions in the binding and cytoxicity of Pseudomonas aeruginosato apical or basolateral membranes of lung airway epithelial cells was tested with fluorescence microscopy on living cells. Binding of noncytotoxic P. aeruginosa strain O1 was assessed with P. aeruginosa that expressed green fluorescent protein. Binding of cytotoxic P. aeruginosa strain 6206 was assessed with FITC-labeled P. aeruginosa; cytotoxicity was determined from nuclear uptake of the impermeant dye propidium iodide. The role of direct contact of P. aeruginosa to epithelial cells was tested with filters with small (0.45-μm) or large (2.0-μm) pores. High transepithelial resistance ( Rt) Calu-3 and cultured bovine tracheal monolayers ( Rt> 1,000 Ω ⋅ cm2) bound P. aeruginosa very infrequently (<1 P. aeruginosa/100 cells) at the apical membrane, but P. aeruginosabound frequently to cells near “free edges” at holes, wounds, islands, and perimeters; cytotoxicity required direct interaction with basolateral membranes. Wounded high Rtepithelia showed increased P. aeruginosa binding and cytotoxicity at the free edges because basolateral membranes were accessible to P. aeruginosa, and dead and living cells near the wound bound P. aeruginosa similarly. Compared with high Rtepithelia, low RtCFT1 ( Rt= 100–200 Ω ⋅ cm2) and EGTA-treated Calu-3 monolayers were 25 times more susceptible to P. aeruginosa binding throughout the monolayer. Cytotoxicity to CFT1 cells (throughout the confluent monolayer, not only at the free edge) occurred after a shorter delay (0.25 vs. 2.0 h) and then five times faster than to Calu-3 cells, indicating that the time course of P. aeruginosa cytotoxicity may be limited by the rate of gaining access through tight junctions and that this occurred faster in low Rtthan in high Rtairway epithelia. Cytotoxicity appeared to occur in a sequential process that led first to a loss of fura 2 and a later uptake of propidium iodide. P. aeruginosa bound three times more frequently to regions between cells (tight junctions?) than to cell membranes of low RtCFT1 cells.

scholarly journals Plasticity of basal cells during postnatal development in the rat epididymis

Reproduction ◽  
2013 ◽  
Vol 146 (5) ◽  
pp. 455-469 ◽  
Author(s):  
Winnie W C Shum ◽  
Eric Hill ◽  
Dennis Brown ◽  
Sylvie Breton
Keyword(s):  
Epithelial Cells ◽  
Postnatal Development ◽  
Tight Junctions ◽  
Vas Deferens ◽  
Structural Plasticity ◽  
Basal Cells ◽  
Cytokeratin 5 ◽  
Rat Epididymis ◽  
Immunofluorescence Labeling

Our previous study has shown that basal cells sense luminal factors by forming a narrow body projection that can cross epithelial tight junctions. As a first step toward characterizing the structural plasticity of basal cells, in this study, we followed their appearance and morphology in the rat epididymis and vas deferens (VD) during postnatal development and examined their modulation by androgens in adulthood. Immunofluorescence labeling for cytokeratin 5 showed that basal cells are absent at birth. They progressively appear in a retrograde manner from the VD and cauda epididymis to the initial segments during the postnatal weeks PNW1–3. At the onset of differentiation, basal cells are in contact with the lumen and their nucleus is located at the same level as that of adjacent epithelial cells. Basal cells then position their nucleus to the base of the epithelium, and while some are still in contact with the lumen, others have a ‘dome-shaped’ appearance. At PNW5–6, basal cells form a loose network at the base of the epithelium, and luminal-reaching basal cells are rarely detected. The arrival of spermatozoa during PNW7–8 did not trigger the development of projections in basal cells. However, cells with a narrow luminal-reaching projection began to reappear between PNW8 and PNW12 in the corpus and the cauda. Treatment with flutamide from PNW10 to PNW12 significantly reduced the number of luminal-reaching basal cell projections. In summary, basal cells exhibit significant structural plasticity during differentiation. Fewer apical-reaching projections were detected after flutamide treatment in adulthood, indicating the role of androgens in the luminal-sensing function of basal cells.

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